This invention relates to evaporative emission control systems for internal combustion engines, and, in particular, to an evaporative emission canister purge system for throttleless internal combustion engine intake systems.
Evaporative emission control or fuel vapor recovery systems have been used in many vehicles in recent years. Such systems include a vapor storage canister that receives and stores fuel vapors emitted from the engine fuel system. Such canisters contain a material such as activated charcoal to absorb and store vapors from the fuel tank. Vacuum within the intake manifold of the engine is utilized to purge the vapors from the canister into the engine induction system during operation of the internal combustion engine.
In recent years, throttleless intake systems have been developed to increase fuel economy. Unlike a conventional spark ignition engine wherein power output is controlled by a throttle valve in the intake tract that produces a vacuum, throttleless intake systems do not provide an appreciable vacuum within the intake manifold. Due to the lack of vacuum within the intake manifold, known evaporative emission control systems do not operate properly with such a throttleless internal combustion engine intake system.
One aspect of the present invention is to provide a canister purge system for throttleless internal combustion engine intake systems. The canister purge system includes a plurality of purged ports, each of which is adapted for connection to an intake port of an internal combustion engine. An evaporative emissions canister is in fluid connection with each purge port. Each purge port includes a valve responsive to pressure changes in the intake port and permitting vapor flow from the evaporative emissions canister into the intake port when a vacuum condition is present in the intake port. The valves prevent flow from the intake port to the evaporative emissions canister when a vacuum is not present in the intake port.
Another aspect of the present invention is a purge system for internal combustion engines including a plurality of intake ports configured to flow air to the combustion chambers of an internal combustion engine. A plurality of intake valves are associated with the intake ports for selectively controlling flow into the combustion chambers. A purge port is in fluid communication with each of the intake ports, and an evaporative emissions canister is in fluid communication with each of the intake ports. A valve is associated with each purge port, and the valves are configured to selectively control vapor flow from the evaporative emissions canister through the purge ports and into the intake ports based at least in part upon the magnitude of the pressure within the intake ports.
Yet another aspect of the present invention is a method for purging vapors from an evaporative emissions container that is operatively connected to an internal combustion engine of the type having an intake tract lacking a throttle valve such that the pressure within the intake ports fluctuates due to opening and closing of the intake valves. The method includes providing a valve for at least a selected one of the intake ports. The valve is operatively connected to an evaporative emissions canister, and the valve is actuated in response to pressure fluctuation in the intake port to selectively permit flow of vapor from the evaporative emissions canister into the intake port.
These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings.